Mame Chd _verified_ -

Input file: game.chd File Version: 5 Logical size: 681,984,000 bytes Hunk Size: 2048 bytes Total Hunks: 332,982 Compression: lzma, flac SHA1: 3b5a... chdman copy -i old.chd -o new.chd -c lzma,flac Create differenced (child) CHD for writable hard disks Parent = read-only base dump. Child stores only changes.

CHD stands for Compressed Hunks of Data . It is a lossless file format designed for MAME/MESS to store dumps of hard disks, CD-ROMs, laser discs, and floppy disks in a compressed, chunk-based manner. mame chd

Example CHD locations in MAME:

Example: chdman -c lzma,flac = LZMA for data, FLAC for audio. | Media Type | CHD size (raw → compressed) | Example | |------------|-----------------------------|---------| | Hard disk (CHD-HD) | 50–90% | chihiro , naomi hard drives | | CD-ROM (CHD-CD) | 30–70% | PlayStation, PC Engine CD, Sega CD | | LaserDisc (CHD-LD) | ~50% | daphne (Dragon’s Lair) | | Floppy (CHD-FD) | 60–80% | Rare, mostly converted to IMD/TD0 | Input file: game

For further reference, see: docs/chd.txt inside MAME source distribution. Official MAME documentation: mamedev.org CHD stands for Compressed Hunks of Data

chdman createhd -o base.chd -i base.raw chdman createhd -o child.chd -i base.chd # creates empty child linked to parent Then in MAME, use -hdd child.chd — writes go to child, parent stays pristine. | Format | Compression | Random access | Write support | Audio tracks | MAME support | |--------|-------------|---------------|---------------|--------------|--------------| | CHD v5 | Excellent | Yes | Diff only | Yes (FLAC) | Native | | ISO | None | Yes | No | No | Yes | | BIN/CUE | None | No (needs index) | No | Raw PCM | Yes | | GDI | None | No | No | Raw PCM | Via CHD | | NRG/MDF | Poor | Partial | No | Partial | Limited |